Topic: Need help on drilling my disc

[jjc]

I have a 550 disc to be drilled.
I have drilled all the 3/8" holes at least 50% and some (25%) all the way through. However I have had nothing but problems. Yes I have a drill press and yes I know all about using lub. But I have spun and destroyed 2 carbide bits.

I'm looking for a drill disc or for someone to finish my drilling.

I would like to get the holes chamfered ( yes I know the pros & cons) but I can do that myself. I bought a carbide chamfering bit

Can you direct me?

[jjc]

I should of added that I know 4 into 1 sells drilled dics. But for there 200$ price I can get it drill here.
I really want to get this one finished but I recall getting the other drilled disc I have for less than 100$.
If I have to spend 200$ now for one disc I will scrap the drilled disc idea and buy 2 used standard discs to get the job done.

[calj737]

If you’re destroying carbide bits while drilling then you’re spinning them too fast. Slow, slow, slow speed with plenty of lube. I’ve done mine on a mill with no problem having used a Centering drill first, then a carbide end mill. Punched them out in under a minute each.

[Gamma]

I used cobalt drills, lots of lube and keep the speed to under 500rpm, apply quite a lot of pressure until you feel it cutting.
I find carbide drills good but very brittle

[robvangulik]

I drilled 2 discs with just 1 HSS steel drill bit, at low speed without any problems.

[Tracksnblades1]

If it’s stainless and you’re using too high of speed and or not using enough feed pressure you can work harden the hole. Stainless is like some other steels. It  can be (work) hardened (tempered) by heat
alone oe with both heat and the coolant as a source of carbon or it’s quenching effect on hot metal..

The rule: start small (less heat) and incrementally step up to your selected size. If you’re using a Bridgeport, use flood cooling and punch the drill or end mill through. You’ll have enough feed pressure and coolant to use a  (good quality high steel) drill bit or end mill.

One draw back with the Bridgeport and an end mill in the collet is centering it. It won’t just self align like a drill press and a vise that’s not bolted down does. The table and vise on a mill won’t allow it.. I wouldn’t try freehanding a vise on any Bridgeport..

Coolant: the best I’ve ever used “DevTap”. Especially hand drilling when you can’t apply adequate feed pressure..
             Bad part about DevTap if it’s still available, make you have blind pups. All kinds of health warnings on it,  even 30
             years ago.

             When you have enough feed pressure, the local machine shop still uses flood cooling for most common stainless
              steels. The tough and hard stainless steels may require experimenting and trying several coolants including the old
              faithfuls’  Real Lard and Real Butter until you find one that works the best…

[jjc]

Under 500 rpm?  I have a multi speed drill press but it only goes down to 800.
I tried several speeds but non in the ranges 'i think' you are talking about. I tried 1200, 1800, & 2800.
I know lub was an issue and to that end I am looking into a way to feed lub while my hands are tied up. I'll look into the suggested lub for future jobs, but I think I'm done on this disc. It's time to turn it over to someone else while I invent a auto lub system . That's going to be a mess. Without lube I had drill bits flying all over. My press is not designed for lub. It is a standard multi speed press  I expect it to be a job getting a lube system set up.
Interesting that one guy used plane bits. Like I said I had bits catch and believe me i reached for that switch fast  I was using lube but my hands were bizzy and i could of used more, hence the auto feed idea.
Also the thought about hardening the metal while cutting. I don't believe it is aluminum. I'm for hardened steel
I was under the impression that a slow speed would cause the bit to bind at the end of the cut . Well, I had binding anyway and that's the worse of the things that went wrong.
So I'm tired of dealing with this and it's going to be out sourced.

[newday777]

Here's a recommended shop for drilling and resurfacing your rotor

https://truedisk.net/

[newday777]

And Godffery, he is a member on here

https://godfferysgarage.com/

[Tracksnblades1]

Under 500 rpm?  I have a multi speed drill press but it only goes down to 800.
I tried several speeds but non in the ranges 'i think' you are talking about. I tried 1200, 1800, & 2800.
I know lub was an issue and to that end I am looking into a way to feed lub while my hands are tied up. I'll look into the suggested lub for future jobs, but I think I'm done on this disc. It's time to turn it over to someone else while I invent a auto lub system . That's going to be a mess. Without lube I had drill bits flying all over. My press is not designed for lub. It is a standard multi speed press  I expect it to be a job getting a lube system set up.
Interesting that one guy used plane bits. Like I said I had bits catch and believe me i reached for that switch fast  I was using lube but my hands were bizzy and i could of used more, hence the auto feed idea.
Also the thought about hardening the metal while cutting. I don't believe it is aluminum. I'm for hardened steel
I was under the impression that a slow speed would cause the bit to bind at the end of the cut . Well, I had binding anyway and that's the worse of the things that went wrong.
So I'm tired of dealing with this and it's going to be out sourced.

Don’t hold the vise or disc by hand. If your centering the drill bit over the center punch mark: with the disc not clamped down
Let the drill bit touch down on the center punch hole with moderate pressure while shutting the drill press off. You should see the unclamped disc move to the drill bits center. While maintaining downward feed pressure on the now stopped dit bit, clamp the piece down. I like using the finish size drill bit for this. Start the drill press and closely observe the drill bit point enter where the drill left its mark before. If you see the drill bit walk or deflect to get back down in its previous hole center, you’ll have to reclamp the disc and try again. They make a centering wobble tool that can speed this up. Once you’re centered over the hole I would change bits to a 1/8”. I like 1/8 pilot holes in harder to drill metals and their small od’s allows higher rpms than large drill bits. The negative if you don’t “feel”  them cutting they’re easier to break off even if they’re perfectly centered to the hole. Move up in size by an 1/8 or more depending on your drill press’s power. I like the finish size drill bit to be at least an 1/8” bigger than the last pilot hole size drilled to prevent self feeding itself into the hole..

Practice centering on a junk one…carry on.

[MauiK3]

I used Tru Disc, very good job.
Im sure Godfrey is good as well.

[jjc]

Took all of the info I got from you guys and was able to get the job completed.
Must have drilled each hole 5-6 times inc chamfering.
All done now

[WideAWAKE]

Clamp your rotor to the table.

Now you have a free hand.

Get an old tuna can, a small basting brush and cutting fluid.

Fill can with fluid, control the downward pressure of the drill with your right hand and use your left hand to baste fluid on your drill bit as needed.

Been done that was in machine shops for ages.

No need for auto lube system, you’re just drilling some holes.